5-lower-alkyl-10-phenyl-5, 10-dihydrophenophosphazine compounds



United States Patent 3,354,214 S-LOWER-ALKYL-10-PHENYL-5,IU-DIHYDRO- PHENUPHOSPHAZINE COMPOUNDS Christ Tamborski, Dayton, Ohio, assignor to the United States of America as represented by the Secretary of the Air Force No Drawing. Filed Sept. 15, 1964, Ser. No. 396,779 8 Ciaims. ((11. 260-576) ABSTRACT OF THE DISCLOSURE Heterocyclic additives, useful in high temperature lubricants, of the structure:

wherein Ris a lower alkyl radical and R is a phenyl or a lower alkyl, made by metalating a N-alkyl-2,2-dihalodiphenylamine with magnesium or lithium and subsequently reacting the diorganometallic compound with phenylor alkyl-dihalophosphine.

tural formula i M R n wherein R represents H or an aryl, alkaryl, alkyl or arylalkyl group and M is a metal or metaloid, have recently been recognized as providing improved oxidation inhibition when incorporated as additives in high-temperature lubricants, particularly low molecular weight ester fluids. While these additives (often referred to as l0l0 additives) have therefore come to be widely used in lubricants for high-temperature applications, they have not been capable of providing the desired and needed improvements in lubricity and the wear-resisting characteristics of the lubricant when it is heated. One illustrative example of the 5-10-10 additives is 5-ethyl-l0, 10 diphenylphenazasiline. Additional examples, as well as other definitions applicable hereto, are provided in the Patent 3,079,414 issued Feb. 26, 1963. It has now been found that the addition or presence of phosphorus in the 5l0l0 molecule will improve the high-temperature anti-wear properties of a lubricant containing such an additive, and it has been found further that the phosphorus may be incorporated in the molecule in such a manner that it does not interfere with the previously enjoyed hightemperature oxidation resistance afforded thereby.

It is accordingly an object of the present invention to provide an improved anti-oxidant and anti-wear additive for high-temperature lubricants.

Another object of the present invention is to provide a phosphorus-containing 5 alkyl 10-phenyl-5,l0-dihydrophenophosphazine compound.

Still another object of the invention is the provision of methods for the formation of S-alkyl-10-phenyl-5,10-dihydrophenophosphazine.

The new compound according to the present invention is 5-alkyl-lO-phenyl-S,10-dihydrophenophosphazine having the following structure wherein R isa lower alkyl group; e.g., CH C H or C H andR' is a phenyl or lower alkyl group; e.g. CH C H or C l-I These compounds are particularly useful as dual functioning anti-wear and anti-oxidant additives in high-temperature lubricants, particularly the low molecular weight esters of polyhydroxy alcohols, and in other base materials such as fluids, greases, elastomers and resins.

In accordance with the present invention, the phosphorus and nitrogen-containing heterocyclic compounds represented by the structural formula above are prepared by metalating a dihalodiphenylamine by a halogen-metal interchange and reacting the metalated intermediate with a phenyldihalophosphine or an alkyldihalophosphine. The dihalodiphenylamine may be N-alkyl 2,2'-dich1or0diphenylamine or N-alkyl-2,2-dibromodiphenylamine. The halogen-metal interchange may be accomplished by the reaction of the dihalodiphenylamine with a straight chain lower alkyllithium, containing from 2 to 10 carbon atoms such as butyllithium, ethyllithium, propyllithiurn, pentyllithium, hexyllithium, decyllithium. This reaction is carried out in an anhydrous organic solvent such as tetrahydrofuran wherein an inert atmosphere such as nitrogen surrounds the reaction medium to exclude both oxygen and water from the reaction. The resultant intermediate in the form of the metalated diphenylamine such as the dilithio-diphenylamine is then reacted with a phosphoruscontaining halide such as a phenyldihalophosphine, e.g., phenyldichlorophosphine.

It has also been found that the dihalo compound can be reacted with elemental magnesium directly to provide a new organo-metallic compound capable of undergoing reactions which are similar to those of the dilithio compound as above described. Thus, if N-alkyl-2,2-dibromodiphenylamine is reacted with magnesium in the presence of tetrahydrofuran or ether as a solvent, the resulting di- Grignard can then be reacted with the phenyldihalophosphine or an alkyldihalophosphine to yield the desirable phosphorus-containing heterocyclic compounds with the phosphorus in the molecule in such a manner that the anti-wear as well as the anti-oxidant properties of the lubricant will be improved and the improvements maintained in high-temperature environments.

The following examples are illustrative of the present invention but are not intended to limit the scope of the same as it is defined in the claims.

EXAMPLE I Preparation of 5-methyl-10-phenyl-5,10- dihydrophenophosphazine A solution of 0.04 mole butyllithium in diethyl ether is added at ice-bath temperature to 6.3 grams (0.0185 mole) of N-methyl-Z,2'-dibromodiphenylamine. After one hour, 3.3 grams (0.018 mole) of phenyldichlorophosphine in milliliters of diethyl ether are added to the reaction mixture. The mixture is then stirred overnight at room temperature whereupon it is hydrolyzed and extracted with ethylacetate to give 3.1 grams (58%) of pale yellow crystals of the S-methyI-IO-phenyl-S,IO-dihydrophenophosphazine with a melting point of from 154 to 157 centigrade. Recrystallization from anhydrous ethanol has been found to raise the melting point to 159-160 centigrade. The calculated analysis of the product (C H NP) is: C, 78.88; H, 5.57; N, 4.84; P, 10.71 and the analysis actually found are: C, 78.92; H, 5.56; N, 4.85; and P, 10.51.

EXAMPLE II S-ethyl-J0-phenyl-5,IO-aihydrophenophosplzazine by Grignard A solution of 10.67 grams (0.03 mole) of N-ethyl-2,2'- dibromodiphenylamine in 45 milliliters of freshly distilled tetrahydrofuran is added dropwise to 1.7 grams (0.07 gram-atom) of magnesium in five milliliters of tetrahydrofuran under a stream of dry nitrogen. The reaction is initiated with a few drops of ethyl bromide. After addition is completed, the reaction is refluxed for two hours, and to the reaction mixture are added 5.00 grams (0.028 mole) of phenyldichlorophosphine in 30 milliliters of tetrahydrofuran. This mixture is then refluxed for twelve hours and hydrolyzed by the addition of saturated aqueous ammonium chloride. Ethyl acetate is added and the mixture filtered whereupon the organic layer is Separated and dried over sodium sulfate. Upon solvent removal a viscous oil is obtained which may be recrystallized from 95% ethanol to yield 2.51 grams (27.5%) of S-ethyl-lO-phenyl- 5,10-dihydrophenophosphazine with a melting point of 85-97 Centigrade. Two successive recrystallizations from 95 ethanol have raised the melting point from 96.5" to 98.0 centigrade. The calculated analysis for C H NP is: C, 79.19; H, 5.98; N, 4.62 and the analysis found was: C, 79.19; H, 5.95 and N, 4.42.

Precise testing has indicated that, while the phosphoruscontaining heterocycles provide oxidation inhibition at least nominally greater than that provided by previously used phenazasilines or other phenazametal compounds, the phosphazines introduce an anti-wear property to the lubricants which preserves the contacting surfaces of the moving parts better than any of the previously employed high-temperature lubricant additives.

While the present invention has been herein described in connection with particular examples and specific embodiments thereof, it is to be understood that the foregoing particularization and detail have been for the purpose of illustration only and do not limit the invention.

I claim:

1. A compound having the formula wherein R is a lower alkyl radical and R is a phenyl or a lower alkyl group.

2. As a compound, 5-alkyl-10-phenyl-5,10-dihydrophenophosphazine.

3. As a compound, Sethyl-lO-phenyl-S,IO-dihydrophenophosphazine.

4. As a compound, S-methyl-lO-phenyl-S,IO-dihydrophenophosphazine.

5. A method for preparing a nitrogen-phosphorus heterocyclic compound comprising the steps of metalating with magnesium an N-alkyl-2,2'-dihalodipheny1amine wherein the halogen is selected from the group of chlorine and bromine and then reacting the metalated intermediate with a phenyldihalophosphine.

6. A method according to claim 5 wherein said N-alkyl- 2,2'-dihalodiphenylamine is one of that class of materials consisting of N-alkyl-2,2'-dichlorodiphenylamine and N-alkyl-2,2-dibromodiphenylamine.

7. A method according to claim 5 wherein said reaction with magnesium is in tetrahydrofuran and the metalated dihalodiphenylamine is subsequently reacted with the dihalophosphine.

8. A method according to claim 5 wherein said phenyldihalophosphine is phenyldichlorophosphine.

References Cited UNITED STATES PATENTS 3,065,251 11/1962 Jones et al. 260576 CHARLES E. PARKER, Primary Examiner.

P. C. IVES, N. WICZER, Assistant Examiners. 

1. A COMPOUND HAVING THE FORMULA
 5. A METHOD FOR PREPARING A NITROGEN-PHOSPHORUS HETEOCYCLIC COMPOUND COMPRISING THE STEPS OF METALATING WITH MAGESIUM AN N-ALKYL-2,2''-DIHALODIPHENYLAMINE WHEREIN THE HALOGEN IS SELECTED FROM THE GROUP OF CHLORINE AND BROMINE AND THEN REACTING THE METALATED INTERMEDIATE WITH A PHENYLDIHALOPHOSPHINE. 